Unpalatable Perennial Grass Invasion in Central-East Argentina Native Grasslands: Processes, Implications and Recovery

In temperate semiarid central-east Argentina, unpalatable perennial grasses (UPG) have been steadily invading native grasslands formerly dominated by palatable perennial grasses (PPG). The objective of this contribution is to provide a synthesis of underlying processes and implications of UPG invasion, as well as recovery strategies. Results have shown that heavy selective grazing on PPG reduces their superior competitive ability. Gaps formed due to reduced competition by PPG provide safe sites for UPG establishment. The development of large, long-lived tussock of UPG, in combination with high standing crop accumulation, impairs PPG establishment even in absence of grazing. UPG produce sclerophyllous tissues, high in fibre and lignin and low in protein and mineral content. Senesced tissues of UPG decompose and mineralize nutrients slower than that of PPG, although they show a relatively low potential to cause nutrient immobilization in soil bacteria. UPG are less productive than PPG, which in combination to their low nutritive value commonly reduce carrying capacity and secondary productivity to half or less of potential values. The analysis and interpretation of current available knowledge point out that conservative and flexible stocking, in combination with controlled grazing and fire, should be implemented to recover and maintain a sustainable use of native grasslands in central-east Argentina

Competitive Interactions Between Palatable and Unpalatable Grasses: Effects of Selective Defoliations of the Palatable Grasses

Selective herbivory of the palatable species appears to be a dominant mechanisms contributing to species competitive replacement in grasslands. Selective herbivory of the palatable species allows unpalatable species to realize a competitive advantage within the community. To test this hypothesis we compare the competitive ability of the unpalatable grasses Stipa trichotoma or S. gyneriodes in the presence of nondefoliated and defoliated plants of the palatable grass S. clarazii. The three species are native to a temperate semiarid grassland of Argentina. The response variables estimated in S.trichotoma and S.gynerioides, at both plant and tiller levels, were higher (P \u3c 0.05) in the presence of defoliated than in the presence of undefoliated plants of S.clarazii. These results support the hypothesis that selective herbivory of the palatable species confers unpalatable species a competitive advantages, contributing to species competitive replacement within the community

Use of Unpalatable Forages by Ruminants: The Influence of Experience with the Biophysical and Social Environment

Unpalatable forage resources (low nutrient density, potentially toxic metabolites) are widespread and represent a challenge for ruminant nutrition, health, and welfare. Our objective was to synthesize the role of biophysical and social experience on the use of unpalatable forages by ruminants, and highlight derived behavioural solutions for the well-being of soils, plants, and animals. Environmental experiences early in life modulate gene expression and promote learning, which alters morpho-physiological and psychological mechanisms that modify behavioural responses and change food and habitat selection. In this process, ruminants can become better adapted to the habitat where they are reared. Moreover, experiential learning provides flexibility in diet selection, which is critical for changing foraging environments. Learned associations between unpalatable and palatable foods, if ingested in appropriate amounts, sequence, and close temporal association, induce the development of preference for the former type of food. In this way, a more uniform use of resources can be achieved from the landscape level down to the individual plant, with the associated benefits to ecosystem integrity and stability. Ruminants can also learn the medicinal benefits of ingesting foods with toxins (e.g., condensed tannins and saponins with antiparasitic properties). This knowledge on behavioural processes can be translated into behavioural applications that provide low-cost solutions to many challenges that producers face in managing sustainable livestock production systems

Contribution of Fdh3 and Glr1 to Glutathione Redox State, Stress Adaptation and Virulence in Candida albicans

Acknowledgments: We thank Aaron Mitchell and Dominique Sanglard for providing the C. albicans protein kinase and transposon mutant libraries, and Louise Walker for the strain CAMY203.Peer reviewedPublisher PD

Arte rupestre en el Abrigo Hornopunta, Jujuy, Argentina

A 50 años que Anales de Arqueología de la Universidad de Cuyo publicara los primeros resultados de Pedro Krapovickas sobre la arqueología del Arroyo Yavi, Jujuy, NO de Argentina, aquí se vuelve sobre el tema. Se trata específicamente del Abrigo de Hornopunta. Son objeto de estudio 21 pinturas naturalísticas, representando hombres y máscaras. Asimismo un grupo de grabados que se hallan fuera del abrigo. Todo pertenece al periodo agro alfarero tardío del 800 DC al 1200 DC y a la Cultura Yavi. La técnica es la pintura lineal y la plana en rojo (distintos matices), verde y violeta. El soporte es una arenisca blancuzca. Los grabados son desprolijos, tal vez por la dificultad con que fueron hechos. Hornopunta es un paredón con una plataforma interna y visera. Posee indicios de intensa ocupación (incluido un fogón). Las paredes miran al Oeste y en ellas el arte es casi inaccesible. Se anuncian en el artículo la posible procedencia de los pigmentos y aglutinantes utilizados.Fifty years afer the "Anales de Arqueología y Etnología, Universidad Nacional de Cuyo" had published Pedro Krapovickas’s first results about the archaeology of the Yavi stream, here I come back to the subject specifically about the Hornopunta rock shelter. Twenty one naturalistic paintings, representing men and masks, have been studied, as well as a group of engravings that are found outside the site. All the art is ascribed to the Yavi Culture, in the late Agroceramic Stage, from 800 AD to 1200 AD. The technique includes linear painting and flat painting in red ( of different hue) , green and purple.The support base is whitish sandstone. The engravings are untidy, perhaps due to the difficulty for making the drawing. Hornopunta show a wall with an internal platform and an awning. There is evidence of intense occupation in it, including a fireplace. The walls look to the West and the rock paintings in these are inaccessible. The possible provenance of used pigments and binding material is also informed in this article.Fil: Fernández Distel, Alicia A.. Universidad Nacional de Juju

Chromosome 9: linkage for borderline personality disorder features.

Objective A large-scale twin study implicated genetic influences on borderline personality disorder (BPO) features, with a heritability estimate of 42%. To date, no genome-wide linkage study has been conducted to identify the genomic region(s) containing the quantitative trait loci that influence the manifestation of BPD features. Methods We conducted a family-based linkage study using Merlin regress. The participating families were drawn from the community-based Netherlands Twin Register. The sample consisted of 711 sibling pairs with phenotype and genotype data, and 561 additional parents with genotype data. BPD features were assessed on a quantitative scale. Results Evidence for linkage was found on chromosomes 1, 4, 9, and 18. The highest linkage peak was found on chromosome 9p at marker D9S286 with a logarithm of odds score of 3.548 (empirical P= 0.0001). Conclusion To our knowledge, this is the first linkage study on BPD features and shows that chromosome 9 is the richest candidate for genes influencing BPD. The results of this study will move the field closer to determining the genetic etiology of BPD and may have important implications for treatment programs in the future. Association studies in this region are, however, warranted to detect the actual genes. © 2008 Wolters Kluwer Health|Lippincott Williams & Wilkins

Replicative Acinetobacter baumannii strains interfere with phagosomal maturation by modulating the vacuolar pH

Bacterial pneumonia is a common infection of the lower respiratory tract that can afflict patients of all ages. Multidrug-resistant strains of Acinetobacter baumannii are increasingly responsible for causing nosocomial pneumonias, thus posing an urgent threat. Alveolar macrophages play a critical role in overcoming respiratory infections caused by this pathogen. Recently, we and others have shown that new clinical isolates of A. baumannii, but not the common lab strain ATCC 19606 (19606), can persist and replicate in macrophages within spacious vacuoles that we called Acinetobacter Containing Vacuoles (ACV). In this work, we demonstrate that the modern A. baumannii clinical isolate 398, but not the lab strain 19606, can infect alveolar macrophages and produce ACVs in vivo in a murine pneumonia model. Both strains initially interact with the macrophage endocytic pathway, as indicated by EEA1 and LAMP1 markers; however, the fate of these strains diverges at a later stage. While 19606 is eliminated in an autophagy pathway, 398 replicates in ACVs and are not degraded. We show that 398 reverts the natural acidification of the phagosome by secreting large amounts of ammonia, a by-product of amino acid catabolism. We propose that this ability to survive within macrophages may be critical for the persistence of clinical A. baumannii isolates in the lung during a respiratory infection